DE2605678C2 - Process for the preparation of formylated phenoxy compounds - Google Patents

Description

(CHJ.

R-O

is equivalent to,

wherein R denotes a hydrocarbyl group with 1 to 20 carbon atoms, which is selected from the group consisting of alkyl, cycloalkyl, aryl and aralkyl groups which can be substituted with one or more substituents which are inert to the oxidation reaction and η is an integer from 1 to 5, the reaction solvent is at least one selected from the group consisting of lower fatty acids having 2 to 8 carbon atoms and anhydrides thereof, which may be substituted by halogen, the reaction solvent in a molar ratio of 03-18 is used in relation to the methylated phenoxy compound, and the catalyst consists of at least one solvent-soluble salt of a metal selected from the group consisting of cobalt, manganese, chromium and nickel, which in the case of cobalt is in a molar ratio of 0.0001 to 1.0 and in the case of manganese, chromium or nickel in a mo lar ratio of 0.0005 to 0.5 with respect to the reaction solvent, but at the same time in a molar ratio of 0.001 to 03 with respect to the methylated phenoxy compound, and the oxidation reaction at a temperature in the range from 100 to 250 ⁰ C and one Pressure of 136 to 98 bar is carried out, the methyl group of the methylated phenoxy compound being selectively converted into a formyl group.

The present invention relates to a method for Production of formylated phenoxy compounds, which is the oxidation of a methylated phenoxy compound in the liquid phase with heating with pressurized oxygen-containing gas with the aid a catalyst in the presence of a reaction solvent includes.

It is based on the state of the art, such as it results from DE-OS 20 25 741,

Formylated phenoxy compounds are used as perfumes, for medicines and as starting materials for other fine chemicals can be used,

It is well known that when a methylated aromatic compound is present with molecular oxygen in Presence of a redox catalyst is oxidized by the methyl group of the aromatic compound

5 Oxidation is converted into a carboxyl group via a formyl group. In this oxidation process however, the rate of oxidation of the formyl group to the carboxyl group is much higher than that Rate of oxidation of the methyl group in the

ίο formyl group. Therefore, the generation of formyl (aldehyde) Compounds with a good yield are extremely difficult due to this oxidation process. For this reason, there has not yet been an industrially feasible method of manufacture of formylated aromatic compounds with a good yield by oxidation of methylated aromatic compounds Molecular oxygen compounds have been proposed.

From DE-AS 19 53 258 the oxidation of p-methoxytoluene with a higher valued metal salt, which serves as an oxidizing agent and is thereby converted into the reduced state. A however, such a method in which the metal salt is used in at least an equimolar amount is uneconomical.

It is therefore an object of the present invention to provide an economical process for the production of formylated phenoxy compounds, in which methylated phenoxy compounds are oxidized in the liquid phase while heating with pressurized oxygen-containing gas in order to produce the formylated phenoxy compounds selectively.
As a result of much research conducted to develop a method of oxidizing methylated aromatic compounds with molecular oxygen to convert the methyl group to a formyl group, it has been found that when methylated benzene compounds are converted to an alkoxy or aryloxy group has been introduced, are oxidized with pressurized oxygen under special reaction conditions, the methyl group of the benzene compounds is selectively oxidized to the formyl group, whereby aromatic aldehydes are provided in good yield.

According to the present invention there is thus a process for the preparation of formylated phenoxy compounds created, which is the oxidation of a methylated phenoxy compound in the liquid phase under heating with pressurized oxygen-containing gas with the aid of a catalyst in the presence comprises a reaction solvent, and which is characterized in that the methylated Phenoxy compound represented by the general formula below

(CH,) "

R-O-

corresponds to where R is a hydrocarbyl group of 1 to 20 Denotes carbon atoms selected from the group consisting of alkyl ·, cycloalkyl *, aryl and Aralkyi groups with one or more

Substituents which are inert to the oxidation reaction and π is an integer from 1 to 5, the reaction solvent is at least one selected from the group consisting of lower fatty acids having 2 to 8 carbon atoms and anhydrides thereof, which are replaced by halogen may be substituted, wherein the reaction solvent is used in a molar ratio of 0.3 to 18 with respect to the methylated phenoxy compound, and the catalyst consists of at least one salt of a metal which is soluble in the solvent, which is selected from the group consisting of Cobalt, manganese, chromium and nickel, which in the case of cobalt in a molar ratio of 0.0001 to 1.0 and in the case of manganese, chromium or nickel in a molar ratio of 0.0005 to 0.5 with respect to the Reaction solvent, but at the same time present in a molar ratio of 0.001 to 0.5 with respect to the methylated phenoxy compound t, and wherein the methyl group of the methylated phenoxy compound is selectively converted into a formyl group, the oxidation reaction is durchgeführc at a temperature in the range of 100 b '250 ⁰ C and a pressure from 1.96 to 98 bar.

In the present invention, the lower fatty acid and / or anhydride thereof both function as Reaction accelerator as well as reaction solvent. Preferred examples of the lower fatty acid are acetic acid, propionic acid, n-butyric acid and isobutyric acid. In the practical implementation of the In the present invention, particularly preferred reaction solvents are acetic acid and acetic anhydride. Halogenated lower fatty acids, d. H. lower fatty acids, which are replaced by halogen such. B. chlorine or Bromine substituted are also included in the category of lower fatty acids:; n, those for the present invention are useful. However, there is no use of such halogenated lower fatty acids less recommendable because of their cost and difficulty in handling. With the present In the invention can be a reaction solvent useful for conventional oxidation reactions. in addition to the lower fatty acid or an anhydride thereof can be used. Preferred Examples of such a reaction solvent are aromatic hydrocarbons such as. B. benzene and Toluene and the corresponding halogenated derivatives. Any organic Solvents can be used if it is only inert to the oxidation reaction. The organic one Solvent which is inert to the oxidation reaction and which will replace part of the reaction solvent can, is in an amount of at most 80 wt .-%, based on the total reaction solvent, used

The catalyst used in the present invention is one or more soluble salts soluble salts of metals selected from the group consisting of cobalt, manganese, chromium and nickel, are selected. In the reaction solvent, such a metal salt generates the metal ion concerned, the then is coordinated with the lower fatty acid or an anhydride thereof and as an effective one Catalyst for synthesizing aldehydes works-In the present invention, any any soluble salt of the metals can be used if it is only soluble in the solvent and in the Is capable of the corresponding in the reaction liquid To produce metal ion, which contains the lower fatty acid or an anhydride of the same as ligand For example, in the present invention, naphthenates, acetylacetonates and salts are preferably lower Fatty acids of the metals mentioned above are used. Particularly preferred catalysts are acetates of these metals.

The reactivity and selectivity of the catalyst used in the present invention ίο varies noticeably with the type of metal ion. One in terms of both activity and selectivity excellent metal additive is cobalt, and the catalytic effectiveness decreases in the following Order from: manganese, nickel and chromium. In the case of the metal ion, the relationship between activity and Selectivity still unclear, but usually the selectivity of the catalyst will be higher when its Activity increases. Accordingly, the scope of the applicable reaction conditions becomes wider when the activity of the catalyst becomes higher.

The amount of at least one lower fatty acid and / or at least one anhydride thereof used in the present invention varies considerably with the kind of the catalyst used and somewhat with the kind of the lower fatty acid itself. Usually, however, the addition of the lower fatty acid in used in an amount corresponding to 0.3 to 18, preferably 7 to Ii molar ratio to the starting compound. In the case that the lower fatty acid anhydride is used, its molar ratio is converted on the basis of the fatty acid. In practice, therefore, the molar fraction of the lower fatty acid anhydride is 1/2 of the nominal molar fraction calculated for fatty acid. When the amount of this reaction solvent used is too small. Both the oxidation rate of the starting material and the selection rate for the aldehyde are lowered, and in extreme cases the reaction will no longer proceed even under the selected reaction conditions. On the other hand, if the amount of the reaction solvent used is too large, no decrease in the selection rate for aldehydes is observed, but the concentration of the starting material is decreased, so that the reaction rate is decreased and the efficiency per unit volume becomes poor. Therefore, the use of an excessively large amount of the reaction solvent is not recommended.

The amount of the metal salt varies considerably with the kind of metal used and somewhat with other reaction conditions. In the case of the cobalt salt, its amount is, for example, about 0.0001 to 1.0 µm molar ratio to the solvent. However, there will be the addition of a relatively large amount of the lower Fatty acid and addition of the cobalt salt in an amount of 0.005 to 0.1 in molar ratio to that Solvent recommended in order to obtain the aldehyde especially in a better yield. When a salt of Manganese, nickel or chromium is used as a catalyst, allows an addition of the metal salt in one The amount only corresponds to the 0.0001 molar ratio to the solvent for the formation of the desired aldehyde. In that case, however, the yield of the aldehyde is remarkably low as compared with the case of FIG Use of cobalt salt. Thus the additions these metal salts in an amount corresponding to 0.0005 to 0.5, preferably 0.01 to 0.05 molar ratio the solvent desirable to use aldehydes

to synthesize in a good yield. If the amount of catalyst used is too small, both the reaction rate and the selectivity are reduced. In the absence of the catalyst the reaction does not proceed any longer On the other hand, the reaction is not disturbed if the Catalyst is added in excess. However, if the reaction takes place in a homogeneous system proceeds, the addition of an excessively large amount of the catalyst to such a degree that the catalyst remains undissolved in the reaction liquid, irrelevant. The presence of a larger amount of insoluble matter in the reaction system is more likely to lead to a negative effect, which consists in the fluidity of the reaction liquid is decreased.

The optimum reaction temperature and the optimum partial pressure of oxygen vary in accordance with the reaction conditions such as. B. Type and amount of catalyst and solvent and the type of starting material used. In a batch reaction system, a reaction ^{temperature within a range from 100 to 230 °} C., preferably 120 to 190 ^° C., and a partial pressure of the oxygen within a range from 2 to 100 bar, preferably 10 to 70 bar, are preferred Satisfactory increase in the yield of aldehydes. In the case of a continuously operating reaction system, the optimum reaction temperature is increased somewhat to a range from 100 to 250.degree. C., preferably 130 to 220.degree. C. Even in the event that a partial pressure of oxygen of only 2 to 10 bar is used, aldehydes can be used with a high selectivity rate can be obtained by appropriately controlling the other reaction conditions. The reaction temperature and the particle pressure of oxygen vary depending on other reaction conditions and are not necessarily limited to the ranges given above. When a soluble salt of manganese, nickel or chromium, which is too low in catalytic activity than cobalt salts, is used as the catalyst, the reaction temperature must be raised to a range slightly higher than that in the case of use a cobalt salt is chosen.

In addition to oxygen itself, various oxygen-containing gases such as B. air and a mixture of air and oxygen can be used as the oxidizing agent in the present invention. However, the use of oxygen is appropriate in view of the fact. - ⁴ ate the reaction is desirably carried out at a relatively high partial pressure of Sauer itoff.

The oxidation process according to the present invention is applied to synthesis of aromatic aldehydes' Λ of the mono- or polymethylated phenoxy. The starting materials used for the process of the present invention are represented by the following general formula:

(CHj) _n

65

where R is a hydrocarbyl group selected from the group consisting of alkyl, cycloalkyl, aryl and aralkyl groups, which may be substituted by one or more substituents inert to the oxidation reaction, and η is an integer of 1 to 5.

The hydrocarbyl group R has 1 to 20 carbon atoms in its molecule. Examples of the hydrocarbyl group are alkyl groups such as B. methyl, ethyl, n-propyl, isopropyl, n-hexyl, n-octyl and isooctyl groups; Cycloalkyl groups such as cyclohexyl, Cyclooctyl, methylcyclohexyl and ethylcyclohexyl groups; Aryl groups such as B. Phenyl-, ToIyI-, XyIyI-, Ethylphenyl-, n-Propylphenyl-, Isopropylphenyl-, Butylphenyl- and naphthyl groups and aralkyl groups such as B. ßenzyl and phenyl groups.

In the present invention, these hydrocarbyl groups can be replaced by one or more inert ones Substituents substituted that do not hinder the oxidation reaction. Examples of the inert substituents in this case are hydrocarbyloxy groups having 1 to 10 carbon atoms such as. B. methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, n-octyloxy, cyclo hexyloxv- and similar cycloassvloxy-, phenoxy- and Benzyloxy groups: Hydrocarbyloxycarbonyl groups such as. B. methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, Isopropoxycarbonyl, n-butoxycarbonyl and n-octyloxycarbonyl groups; and halogen atoms joke. B. chlorine and bromine atoms. These inert substituents can also be replaced by a similar one inert substituents or several substituents * be substituted. Hydrocarbyl groups represented by a or more reactive substituents such as. B. substituted hydroxyl, mercapto and amino groups which interfere with the oxidation reaction are unsuitable as the hydrocarbyl group R. The free hydroxyl or mercapto group exerts a self-oxidation-inhibiting effect and strongly prevents the course of the Oxidation reaction of the present invention. Because a tertiary carbon atom is lighter than the methyl group is oxidized, the presence of such a tertiary carbon atom can reduce the selectivity in interfere with the reaction. If z. B. a tertiary carbon atom in the substituent R in the starting phenoxy compound of the general formula given above with a methyl group in the meta position of the benzene ring is present, which is to be converted into the formyl group and is less reactive than the tertiary carbon atom, the rate of selection with respect to the aldehyde product in the Oxidation reaction seriously reduced. However, the presence of such a tertiary carbon atom prepares no trouble if a methyl group in the \ Para position of the benzene ring, the is more responsive. is oxidized.

In the ring-methylated phenoxy compounds used as starting materials in the present invention, two or more methyl groups can be present in the benzene nucleus, but in this case these methyl groups have a tendency. being oxidized in the following order: para, ortho and meta to the substituent RO-. Thus, the Ausgangsphenoxyverbindungen which have a Methylgfuppe in the para = 5tellung its benzene nucleus, selectively oxidized in the p-methyl group to form p-Formylphenoxyprodukte, in a similar manner, starting materials not methyl ethyl group in de ^r para position on have their benzene nucleus, but have two methyl groups in the ortho and meta ^ positions, preferably in the

Ortho-methyl group oxidizes to o-formyl-m-methyU To make products predominant. According to the present invention, mono-formyl products in a high yield and with a high selection rate of methylated phenoxy starting materials, the carry at least two methyl groups on their benzene nucleus by appropriately controlling the reaction conditions getting produced. Although also diformyl products from the dimethyl or trimethyl starting materials can be produced, the yield and the selection rate in this case are so bad that it is not worth using on an industrial scale. This is due to the reason that the formyl group first formed by oxidation of a methyl group is more easily oxidizable than that remaining methyl group or the remaining methyl groups and so before the oxidation of the remaining Methyl group or the remaining methyl groups to formyl group or to formyl groups itself is oxidized to the carboxyl group. Accordingly, the present invention becomes advantageous on the production of mono-formyl production in applied on an industrial scale. In the event that starting materials. which have several methyl groups, can only be used as a mono-formyl product through suitable control of the Response time can be made from it.

Examples of the methylated phenoxy compounds used as starting materials for the inventive Procedures used include:

Tolyoloxymethane (or methoxytoluene),
Tolyloxyethane (or ethoxytoluene),
Tolyloxy-n-propane (or n-propoxytoIuene),
Tolyloxyisopropane (or isopropoxytoiuol),
Tolyloxy-n-butane (or n-butoxytoluene),
Tolyloxy-isobutane (or isobutoxytoluene),
Tolyloxycyclohexane

(or cyclohexyloxytoluene).
Tolyloxymethylcyclohexane

(or methylcyclohexyloxytoiuol),
Tolyloxybenzene (or phenoxytoluene),
Tolyloxytoluene (or ditolyl ether).
Xyloxymethane (or methoxyxylene),
Xyloxyethane (or ethoxyxylene).
Xyloxy-n-propane (or n-propoxyxylene),
Xyioxyisopropane (or isopropoxyxylene),
Xyloxy-n-butane (or n-butoxyxylene),

15 xyloxycyclohexane (or cyclohexyloxyxylene),
Xyloxybenzene (or phenoxyxylene),
Xyloxytoluene (or tolyloxyxylene),
Mesityloxymethane (or metnoxymesitylene),
Mesityloxyethane (or ethoxyrnesitylene),
Mesityloxy-n-propane

(or n-propoxymesitylene),
Mesityloxy * n * butane (or n-Buiöxymesiiylen),
Mesityloloxyeyclohexane

(or cyclohexyloxymesitylene),
Mesityloxybenzene (or phenoxymesitylene),
Mesityloxytoluene (or tolyloxymesitylene),
Methoxyphenyl tolyl ether.
Phenoxyphenyl tolyl ether.
Methoxycarbonylphenyl tolyl ether.
Methoxyäthyltolyläther and
Methoxycarbonyl ethyl tolyl ether.

The process of the present invention can be carried out batchwise or continuously, but the latter is a continuous process in which control of the reaction temperature is easy desirable in view of the fact that the reaction is completed in a short period of time is to synthesize the aldehyde product with a good yield, and that the oxidation reaction itself is highly exothermic, and in view of the fact that an excessively higher reaction temperature a reduction in the selection rate in relation

jo brings on the aldehyde product

Separation and processing of the aldehyde product produced, the catalyst, the solvent and the unreacted starting materials from the reaction mixture are obtained by processes made known to those skilled in the art. For example, the aldehyde product can easily be mixed with a high yield can be obtained by removing the lower fatty acid in the reaction mixture Distillation is removed under reduced pressure, a

■ »ο solvents such as B. toluene to the distillation residue is added, the mixture is subjected to centrifugal separation with cooling to thereby remove the catalyst, and then the remaining liquid is distilled under reduced pressure.

The present invention will now be explained in more detail with reference to exemplary embodiments however, they are not intended to limit the scope of the invention in any way.

example 1

Into a 300 ml stainless steel autoclave equipped with a stirrer, thermometer and gas inlet were placed 30 g of p-methoxyethylene, 184 g of acetic acid and 12.0 g of cobalt acetate tetrahydrate. The liquid mixture was kept at 90 to 120 ° C. while it was stirred vigorously. From a pressure tank, gaseous oxygen was introduced into the autoclave through a pressure regulator and the pressure of the oxygen was kept at 60 bar entered a violent oxidation reaction so that it was difficult to keep the reaction temperature within a defined temperature range, however, extreme care was taken to keep the reaction temperature as defined as possible, and the amount of oxygen consumed became roughly from the decrease in oxygen pressure in the oxygen pressure tank calculated At the time when almost the required amount of oxygen was absorbed, the reactor was rapidly cooled to stop the reaction. The reaction product was analyzed by gas chromatography Gas chromatography at elevated tempera The column material used was silane-treated diatomaceous earth on which there was 10% by weight of silicone oil. This method of analysis was common for all of the examples. The procedure for the oxidation reaction in the following examples was completely identical to that used in this example, with the inclusion of Example 14 using a flow-through system

Tabel

3 *)

115 126
115 145
120-134
91 98

ίο

Πχρ. Reactionary Reaction Reaction Selection rale for No. lcmpcraUir Time RiIc of p-McllioxybeiizalcIehyd p-methoxytoliol CO (min) (%) (MoI-%)

2.8
2.1
3.5
8.0

89.8 51.8 98.6 18.9

71.2
70.2
35.3
47.8

*) In this experiment, the reaction is so tibcrinnBip. that the Selefclion calls for p-methoxybenzaldehyde was decreased.

Example 2

Into the reaction apparatus described in Example 1 70 g of p-methoxytoluene, 172 g of acetic acid and 14.0 g of cobalt acetate tetrahydrate were added. The Oxidaiiunsrcukiiöii would be in the same

Example 1 described carried out. Since the purpose of this example was to evaluate any influence of the oxygen pressure was provided to maintain the reaction temperature to 150 ⁰ C. In reality, however, the temperature could not be fully maintained at 150 ° C because of a violent exothermic reaction, so that the maximum temperature reached around 165 ° C. A result of the experiments is shown in Table 2.

Table 2

Exp. Sauersloff Reaction Reaction Selection rate for No. pressure Time rate of p-Methoxybenzaldehvd p-methoxyloluene bar (min) ( %) (Mol%) 1 15th 60 58 56 2 30th 12.0 58 67 3 45 6.5 56 70 4th 60 4.0 66 73 5 90 1.0 53 71

Example 3

In the reaction apparatus described in Example 1, 70 g of p-methoxytoluene, 172 g of acetic acid and Cobalt acetate tetrahydrate in an amount corresponding to 0.01 to 0.5 molar ratio to the p-methoxytoluene given. The oxidation reaction was carried out in the same manner as described in Example 1 to to investigate any influences of the concentrations of the catalyst. The oxygen pressure was 15 bar, and the reaction temperature was kept at 150 ° C. (In reality it reached the maximum Reaction temperature, however, temporarily up to about 165 ° C) A result of the experiments is shown in Table 3 specified.

Table 3

Exp. XY *) Reaction Reaction Selection rate for No. (molares Time rate of p-methoxybenzaidehyde Relationship) p-methoxytoluoi (min) (%) (Mol%)

1 0.01 28 54 43 2 0.05 32 64 56 3 0.1 61 83 51 4 **} 0.1 53 67 55 5 0.2 90 72 45 6th 0.5 279 60 38

*) X = cobalt acetate tetrahydrate Co (CH ₃ CO ₂ ), -4H ₂ O

j- = p-methoxytoluene H ₃ C - C ₆ H ₁ - 0 (CH ₃ ) (p-position) **) The experiment was carried out under a pressure of 10 bar oxygen.

Example 4

In this example, influences of the concentrations of the catalyst in the case of changing the mixing ratio of p-methoxytoluene to acetic acid examined. In the same in example 1 EeafctionsapparaiuT described were 7ugp-Methöxytoluol, 60 g of acetic acid and a predetermined amount

Given cobalt acetate tetrahydrate. The reaction was carried out in a manner similar to that described in Example 3 is described. After a two hour

Table 4

For reaction of the mixture, the product was subjected to analysis, with a result as shown in Table 4 is specified, has been obtained.

(E JCp.

No.

XY molars
relationship

fccaklionsralc of p-Metlioxyloliiol Sclcklionsnilc for

p-methoxybenzaldehyde

36 36 41 50 45 46 47 *) In these [-expenmenten the catalyst did not completely dissolve in the Reaklionsriüssigkeil

1 0.001 13th 2 0.005 44 3 0.01 52 4th 0.05 54 5 0.077 59 6 *) 0.1 55 7 *) 0.2 43

■ Example5

In the reaction apparatus described in Example 1 were 70 g of p-MethoxytoIuol, 21g of acetic acid and Given 14.0 g of cobalt acetate tetrahydrate. The mixture was stirred for 2 hours at different reaction tem-

Table 5

Temperatures brought to reaction, while the Saueron clnfMrlirlf to 1 ^ i Kar cjf * ha \ tt * n ιι / ιι, τΙα ktttnrttnA "j» »» violent exothermic reaction, the maximum reaction ^{temperature was 10 to 15 0} C higher than the predetermined temperature point. A result of the experiments is shown in Table 5.

f-.xp. Response temperature (C) Reaction Selection rate for No. previous maximum rale of ρ methoxybenzaldehyde correct value p-Vlethoxytoliiol value (X) (Mol%)

1 100 105 12th 46 2 125 140 69 46 3 150 160 40 68 4th 180 195 25th 34 5 200 215 23 28

Example 6

In the same reaction ap- -to described in Example 1 30 g of p-methoxytoluene and 12.0 g of Koebalt acetate tetrahydrate were used and various kinds of solvents in an amount corresponding to 10 molar ratio given to the p-methoxytoluene used. The reaction was carried out under an oxygen pressure that was up to 60 bar was maintained, and carried out at a reaction temperature of 130 ° C, (in reality the maximum temperature, however, up to about 145 ° C), whereby

Table 6

a result as shown in Table 6 was obtained. In the case when a mix of Solvents was used, the total amount of solvents was based on a molar ratio set from 10 to the p-methoxytolu ^ l used In the case of using acetic anhydride, its amount was given in terms of acetic acid calculated. In other words, when acetic anhydride was used alone, their amount was the same a molar ratio of 5 to the methoxytoluene used.

Exp. Type of solvent Reaction Response rate of Selection rate for No. (Numbers indicate molar ratio) Time p-methoxytoluene p-methoxybenzaldehyde (min) (%) (MoL-%) 1 acetic acid 2.7 75.3 72.2 2 *) Acetic anhydride 3.0 92 ° **) 47.2 3 Butyric acid 2.8 78.2 43.5 4th Propionic acid + acetic acid (1: 1) 2.7 77.1 49.2 5 Propionic acid + isobutyric acid + butter acid (2: 1: 2) 3.1 69.1 39.8 6th Acetic acid + acetic acid aihydride (1: 1) 2.8 79.1 70.1 7 *) Monochloroacetic acid 3.0 43.0 33.7 8th***) acetic acid 11.0 50.3 58.3

*) These experiments were carried out under an oxygen pressure, which was kept at 50 bar, and at a reaction temperature of

150 ⁰ C carried out.

**) In this experiment, the reaction was so excessive that the selection rate for p-methoxybenzaldehyde was reduced. ***) This experiment was carried out under an oxygen pressure which was kept at 5 bar.

Example 7

In dip. same reaction apparatus described in Example 1, 30 g of p-methoxytoluene, given a predefined ^r> fie amount of a solvent and a predetermined concentration of a cobalt salt catalyst. The oxidation reaction was carried out under an oxygen pressure was maintained at 5 NC bar, and at a reaction temperature of 13O ⁰ C, whereby a result was obtained as shown in Table 7

Table 7

is specified. Table 7 also shows, as comparative examples, the data obtained in the case that the lower fatty acid or an anhydride thereof was not present. As can be seen from the table, the absence of the lower fatty acid or anhydride causes a remarkable reduction thereof the yield of p-methoxybenzaldehyde.

Exp.
No.

Solvent * ¹ )

Catalyst*')

Response time (min) Response rate from
p-mellioxytoluene
I%)

Sclionsraic for p-melhoxy benzaldehyde l

Acetic acid (5)
+ ■ Ben / ui (7.55
Acetic acid (3.5)
+ Benzene (9)
Acetic acid (3.5)
+ Chlorobenzene (

Co (OAc), * -)

H'.ii

Co (OAc), (0.14) + Co-N * ') (0.06) Co (OAc), * -') (0.14) + Co-N * ¹ I (0.06)

(Comparative examples)

Benzene (101 Co-N * ')

Benzene (10)

Cobalt acelylacetonate (0.2)

2.0 18.5 23.0

150 18.0 76.4

24.4
44.2

8.0
13.9

29.2 39.7 47.4

10.0 18.2

* ') The numbers in brackets denote the amount of the added solvent or catalyst in molar values

Ratio / u to the starting p-methoxytoluene. * ^! ) Cobalt acetate tetrahydrate
* · ') Cobalt naphthenate.

Examples

In the reaction apparatus described in Example 1, oxygen pressure, which was kept at 50 bar, and at

30 g of p-methoxytoluene, 184 g of acetic acid and a reaction ^{temperature of 150 °} C. were carried out,

Acetate of various kinds of metals in an amount with a result as shown in Table 8

corresponding to 0.2 molar ratio to the p-methoxytoluene was obtained, given. The oxidation reaction was under one

Table 8

F.xp.
No.

metal

j
4 *)

manganese

nickel

chrome

manganese

nickel

Reaction Reaction Selection rate for Time rate of p-methoxybenzaldehyde p-MethöxvtoIuol (min) (%) (Mol.- ⁰ / ») 28 55.2 49.3 55 54.9 23.6 50 12.3 54.8 8th 44.8 294 31 57.3 20.0

*) In this experiment, 209 g of acetic anhydride% 'were used instead of acetic acid, while

the amount of p-methoxytoluene was reduced to 20 g.
**) In this experiment, instead of acetic acid, a mixture of 59 g of acetic anhydride and

92 g acetic acid used.

Example 9

The oxidation of p-methoxytoluene was carried out using acetic acid, or acetic anhydride a mixture of acetic acid and benzene as a solvent and

Nickel acetate tetrahydrate [Ni (CH ₃ CO ₂ ) Z - 4H ₂ O],

Manganese acetate tetrahydrate [Mn (CH ₃ CO ₂ ) ₂ ■ 4H ₂ O]

or

Chromium acetate monohydrate [Cr (CH3CO2) 3 · H ₂ O]

carried out as a catalyst using the same reaction apparatus described in Example 1 and changing the molar ratios of the solvent and the catalyst to the Starting p-methoxytoluoI was a series of Experiments performed under the following predetermined reaction conditions:

Volume of the reaction liquid 200 cm ³

Oxygen pressure 50 bar

Reaction temperature 160 ° C

A result
specified,

of the experiments is in Table 9

Tabel 9 solvent K.atal> - Reaction Response rate of Selection rate for Exp. sator Time p-methoxytoluene p-methoxybenzaldehyde No. (min) (%) (Mol.-5'o) Acetic acid (0.6) nickel 45 64 34.3 1 (0.01) Acetic acid (12.5) nickel 15.5 33 15.1 2 (0.01) Fs-acidic acid (0 6) manganese 25th 14.2 19.9 3 (O.ni ( ! »Iisaurc i! ί.5! + ίί <.η / ι> 1 i 1 i manganese 23.5 46.S 5.1.8 4th (0.2) " 1 vsiusaurc (.s.S) + benzene (3.7) manganese 28 30.7 26.4 5 (0.2) " I ssipsaiire (111 · Ben /. 'J> nickel 58 59.2 20.5 6th 1 vsia acid (0.6) C hrcin
ti ' ti ¹ ■ 130 5.2 28.1 7th I sMgic acid additive (0.6) ι *. * 'i
Chr.) Η 30th 21.5 16.6 S. (0.01

*) The numbers in brackets indicate an amount of the added solution or catalyst in molar proportions the starting point methoxytoluene

Example 10

Oxidation of p-methoxytoluene was carried out in the same manner as described in Example 1, with the exception that a mixture of 100 g of acetic acid, 50 g of acetic anhydride and 30 g of propionic acid was used as the solvent in place of acetic acid and that a mixture of 10.0 g of cobalt acetate tetrahydrate and 10.0 g of nickel acetate tetrahydrate were used as the catalyst. Although the reaction was carried out at a reaction ^{temperature of 120 °} C., the maximum temperature reached up to 130 ^° C., which was due to a violent exothermic reaction. After 23 minutes passed, the amount of oxygen absorbed reached a required value. The reaction vessel was then rapidly cooled and the liquid product was subjected to analysis to find that the reaction rate of p-methoxytoluene was 573% and the selection rate for p-methoxybenzaldehyde was 623 Mol%.

Example 11

With the exception that a mixture of 3.0 g of manganese acetate tetrahydrate, 1.0 g of chromium acetate monohydrate and 1.0 g of nickel acetate tetrahydrate as a catalyst instead of cobalt acetate tetrahydrate as in Example 1 Oxidation of p-methoxytoluene was used in the same manner as described in Example 1 is, under an oxygen pressure maintained at 40 bar and carried out at a reaction temperature of 150 ° C When the required amount of oxygen was absorbed after the lapse of 17 minutes, was the reaction vessel cooled rapidly and the reaction product subjected to analysis, being found became that the reaction rate of p-methoxytoluene was 49.5% and the selection rate for p-methoxybenzaldehyde Was 39.1 mol%.

Example 12

With the exception that o- or m-MethoxytoluoI was used in place of p-methoxytoluene in Example 1, the reaction was carried out in the same manner as in FIG Example 1 described manner carried out under an oxygen pressure maintained at 50 bar and at a reaction temperature of 125 ° C. In the case of Oxidation of o-methoxytoluene taking a reaction time of 154 minutes, the reaction rate was

so of o-methoxytoluene 34.0% and the selection rate for o-methoxybenzaldehyde 56.7 mol%. In case of Oxidation of m-methoxytoluene, which required a reaction time of 25 minutes, was the reaction rate of m-methoxytoluene 22.8% and the selection rate for m-methoxybenzaldehyde 195 mole percent. When the oxidation reaction of m-methoxytoluene was carried out at 150 "C for 4.5 minutes, the reaction rate was the same 375% and the selection rate for m-methoxybenzaldehyde 35.1 mol%.

Example 13

When the reaction temperature was 25 minutes at 125 ⁰ Cgehalten in Example 8 and Köbaltnaphthe-Hat was used as the catalyst, the reaction rate, as a result of p-methoxytoluene of 37.7%, and the selection rate of p-methoxybenzaldehyde of 64.0 mol% obtain.

230 237/225

Example 14

An oxidation reaction was carried out with a stainless steel fraction tower which was provided with a jacket with an internal diameter of 10 mm and a height of 1000 mm. From a reservoir Di-octyl phthalate was maintained at 130 ⁰ C fed and circulated through the jacket so that Reaktionsflüssi | keep jkeit at a defined temperature. A liquid mixture containing 40 g of p-methoxytoluene, 200 g of acetic acid and 8 g of cobalt acetate tetrahydrate was introduced into the fractionating tower from the lower part thereof at a flow rate of 30 ml / min. On the other hand, oxygen was introduced at a flow rate of 900 ml / min ( calculated at normal pressure and temperature) through a perforated plate (50 holes with a diameter of 0.4 mm were evenly distributed over the entire plate), which was attached to the lower part of an inlet for the liquid starting material. The reaction pressure was kept at 50 bar, and the product removed from the reaction vessel was fed to a water-cooled gas separation plant, where the gaseous phase was separated from the liquid phase. Analysis of the liquid phase showed that the reaction rate of p-methoxytoluoil was 73% and the selection rate for p-methoxybemaldehyde was 79 mol%.

If the liquid starting material consists of 40 g of p-Mi thoxytoiuoll, 150 g of acetic acid, 50 g of acetic anhydride, 4 g cobult acetate tetrahydrate and 4 g manganese acetate tetrahydrate was composed in this experiment, the reaction rate was p-methoxytoluene 2 .. '% and the Si lection rate for p-methoxybenzaldehyde 50 mole percent.

In the event that the oxidation reaction is similar with a liquid starting material consisting of 40 g of p-methoxytoluene, 200 g of 10% strength by weight aqueous acetic acid and 20 g of cobalt acetate tetrahydrate was composed.

was carried out, the reaction rate of p-methoxytoluene was 40% and the selection rate for p-methoxybenzaldehyde 73 mole percent.

Example 15

To 1.5 moles of p-cresol was added 1 mole of KOH, 1 mole of various types of commercially available bromine hydrocarbons and added a very small amount of powdered copper. The mixture was stirred well and refluxed for 2-3 hours to give a product of the following general terms Synthesize Formula:

15 -CH,

The product was washed through and through with an aqueous solution of alkali and then under distilled under reduced pressure to produce a starting material suitable for an oxidation reaction should be used. The same as described in Example 1 reaction apparatus was with 30 g of one Starting material of the general formula given above and given amounts of acetic acid and Cobalt acetate charged. An oxidation reaction of the starting material was carried out under a pressure of 20 bar carried out maintained oxygen pressure, after the course of a certain start-up time a violent Reaction took place and the reaction temperature was increased rapidly. The reaction product was, as described in Example 1 described is subjected to gas chromatography. A result of this is shown in Table 10 specified. The reaction product was determined by a combined use of gas chromatography-mass spectroscopy Method (GC-MS method) and the nuclear magnetic resonance method (NMR method) identified.

Table 10 Substituent R Z / Y " ¹ ) X / Y ' ^{+ l} ) reaction

(molares (molar temperature

Ratio) ratio) (° C)

Start-up reaction time

(sec) time

(sec)

10
10
10
10
13th
13th

11
13th

10
10

0.3

0.01

0.3

0.3

0.1

0.05

0.3
0.3

0.3
0.2

155-192 165-168 158-178 170-193 161-193 155-179

185-198 180-200

165-199 180-202 705

480

435

113

0 35
28 38

Response rate CA)

37.8
71.0
90.3
65.1
75.2

24.0
38.5

50.0
26.7

Selection rate for aldehyde (MnI-Vo)

65.9
39.9
50.0
37.3
49.5
43.7

77.0
52.1

63.9
68.7

continuation

Substituent R

ZZY ^{1 + 1} ) X / Y "" ¹ ) Reaction Start-up Reak React Seleklions (molares (molares temperate Time ions functional rate for Relationship) Relationship) ( ⁰ C) (sec) Time raie aldehyde

(sec)

12.5

0.2

0.2

0.3

0.3

170-200

180-200 2840

20th

120

100

61.9

61.1

56.1

31.5

80 54.6 14.9

155-177

0 90 67.9 16.8

⁺ ') Z = acetic acid

X = Co (CH ₁ COj), 4H ₁ O

Y '= RO- <f O

-CH,

^{+ 2} > Prepared from diethyl sulfate and p-cresol according to the process described in Example 17 ^+} ) Commercially available compound which has been purified in the usual way ⁺⁴ ) Synthesized from p-bromotoluene and p-alkylphenol

^{+ s} ) Synthesized from m-bromotoluene and p-ethylpheno!

(Note: methyl group present in this connection in meta-definition)

Example 16

Methyl-substituted diphenyl ethers of the general formula

in which the positions 1 - 5 and Γ to 5 'are replaced by H or CH3 residue were occupied by commercially available methylphenols and bromobenzene or Bromotoluene synthesized by the method described in Example 15 The resulting methyl-substituted Diphenyl ethers were satisfactorily purified in a manner similar to that in Example 15 was described, and then subjected to the oxidation reaction. A result of the experiments is in Table 11 given. The reaction products were

Table 1!

by topping or separating the solvent from the reaction mixture under reduced pressure, extracting the residue with water and toluene, and then desiccating the toluene layer under reduced pressure. In all of these experiments, the formation of dialdehydes was not observed. The methyl substituents in the starting materials were converted to formyl groups in the order of p, o and m positions to the position of the KC substituent. The tendency of the transformation resulted namely in the relation p->o-> m-position. For example, in the case that the starting material contained methyl groups in the o- and p-positions, the p-methyl group was preferentially oxidized to the formyl group. Similarly, if the starting material contained methyl groups in the o- and m-positions, the o-methyl group was preferentially oxidized to the formyl group. In Table 11, the grouping "CH3CO" is indicated simply by "Ac" and the formula "H ₂ O" as "Aq".

Exp.
No.

Position of
Methyl subst. **)

Solvent [amount used) *) Catalyst [amount used] * l

11 1

11 2
Il 3

11-4
11-5
li-6

2. .V

1.3 * 5
1.2

AcOH [5) + (AcO) ₂ O [3] + propionic acid [2] AcOH [5] + benzene [7.5] AgOH [12.5]

AcOH [IS]

AcOH [10] + (AcO) ₂ O [5]

Butyric acid [13] JCo (AcO) ₂

JNi (AcO) ₂

Co (AcO) ₂

Mn (AeO) ₂

Ni (AcO) ₂ '

Cu (AcO) ₂

Co (AcO) ₂

Co (AcO) ₂

JCo (AcO) ₂ ■

[Mn (AcO) ₂

4Aq [0.1] 4Aq [0.1] 4Aq [0.2]

qIJ 4Aq (0.05] 1 Aq [0.05] 4Aq [0.5] 4Aq [OJJ 4Aq [0.2] '4Aq [0.2]

2!

continuation

Position of
Melhyl Subs. **)

Solvent [amount used] *) Catalyst [amount used] *)

1, 2, 3 '

2, 3, 2 '

1,3,5, 1 '

AcOH [10] AcOH [5] + chlorobenzene [5] + toluene [3]

AcOH [8] + (AcO), O [2]

Co (AcO) ₂ -4Aq [0.3] Co (AcO) ₃ -4Aq [0.2] Co (AO) ₂ -4Aq [0.3]

Table 11 continued

Ej «p.
No.

Reaction temperature

Oxygen

pressure

(bar)

Start-up time (set) response line
(sck)

Reaction rale

Selection range for aldehyde

11 1 185-196 20th 0 70 30.8 29.4 11-2 180-194 30th 525 195 67.3 18.6 H-: 180-185 30th 180 390 39.6 29.2 11 4 180 183 45 150 8th 68.2 35.1 11 5 18O-193 60 30th 21 72.1 37.9 116 180-185 40 135 40 58.3 31.5 11 7 155 191 40 0 35 71.5 όϊ.δ 11 8 180 195 60 611 137 49.1 25.3 11 9 160 195 40 0 42 59.5 55.5

*) In values of the molar ratio to the starting material used. **) Position of the methyl substituent or substituents in the starting compound.

Example 17

In 200 ml of water, 0.5 mol of cresol and 0.5 mole of NaOH were dissolved While the liquid temperature of the solution was maintained at 65 to 70 ⁰ C, 0.5 mole of diethyl sulfate dropwise over a period of 15 to 20 minutes with vigorous stirring added to the solution. After the addition of the diethyl sulfate, the liquid mixture was stirred under reflux for about 30 minutes, and the oily phase thus formed was thoroughly washed with a 10% aqueous

Table 12

Solution of NaOH and then washed with water, dried and distilled under reduced pressure

subjected to synthesize ethoxytoluene. A Autoildave was made with 30 g of this Ethoxytoluene and predetermined amounts of a solvent and a catalyst charged, and one Oxidation reaction was carried out in a similar manner

performed as described in Example 1 A The result of these experiments is given in Table 12.

Exp. Position of solvent catalyst No. Alhoxy group [amount used | *) ! amount used) *) 12 1 para Acetic anhydride [5] Co (AcO) ₂ -4Aq [0.2] 12 2 para Acetic acid [10] Mn (AcO), -4Aq KU] 12 3 meta Acetic acid [10] Co (AcO) ₂ -4Aq [0.2] 12 4 para Propionic acid [10j | Co (AcO) ₂ -4Aq [0.3] 12 5 ortho Butyric acid [15] Cr (AcO) ₂ -4Aq [0.2] Ni (AcO) ₂ -4Aq [0.2] Table 12 continuation F.xp. Reaction Oxygen reaction Response selection rate No. temperature pressure zeu rate for aldehyde ΓΠ (bar) (sec) (%) (MoL%)

12 1
12 2
12 '
12 4
12-5

155
160
165
160

170
168
171
180

20 20 20 20 40

250 176 115 35 355

165-171
*) In values of the molar ratio to the starting rule used 63.2
47.1
28.7
45.8
49.3

56.7 31.9 30.4 60.8 18.5

Example 18

Using the same procedure as described in Example 15, hydrocarboxytoluene compounds are used

65

iiö-

of commercially available phenols »with the

following structural formulas A 'to C and commercially available p-bromotoluene with the degree of purity »Special« according to the Japanese industrial standard (JlS-spe-

cial grade). Those of the phenols A 'to C The products manufactured are labeled A to C, respectively.

Λ '

OC-H,

on

Cl-

B 'OH

OCH,

To 40 g of the hydrocarbyloxytoluene compound were 100 g acetic acid and 12.5 g cobalt acetate

Co (CH ₂ CO ₂ ) J · 4H ₅ O
added. An oxidation reaction was carried out in a manner similar to that described in Example 1, under an oxygen pressure maintained at 50 bar. A result of the experiments is shown in Table 13.

Table 13

Starting material reaction- reaction time

temperature

( ⁰ C) (sec)

Reactionary

A.
B.
C.

180-205 188-202 192-207

CH,

45 29 71 75
38
58

H ₅ C ₂ -O

CH ₃ H ₅ CO- / ES

ClU

CH ₃ CH ₃

Selection rate for aldehyde

61
53
45

Similarly, the polymethylated was similarly under a pressure of 20 bar

Phenoxy compounds D and E carried out by conventional maintained oxygen pressure, with 200 g

O-alkylation of the corresponding polymethylated 45 acetic acid were used as solvents. A

Phenols with diethyl sulfate and dimethyl sulfate, corresponding to the result of the experiments is given in Table 14, chend D and E, synthesized. An oxidation reaction

Table 14 Reaction
temperature
( ⁰ Q reaction time
(sec) Response rate Selection rate for
aldehyde Starting material 150-168
140-153 53
230 72.4
62.2 36.5 *)
6.7 **) D.
E.

*) Selection rate for

CHj

HsC ₁ -O

CHO

**) Selefctionsrafe for

CHj

HjC- O

CHO CH,

Claims (1)

Claim: Process for the preparation of formylated phenoxy compounds, which involves the oxidation of a methylated phenoxy compound in liquid phase with heating with pressurized oxygen-containing Comprises gas with the aid of a catalyst in the presence of a reaction solvent, characterized in that the methylated phenoxy compound of the following general formula